The present invention relates to a wall coupling and is particularly concerned with such a coupling which restrains two adjacent wall parts in overlying relationship from relative displacement over each other. Typically one wall part may be on a container lid while the other wall part is on the container body so that the coupling provides a means for retaining the lid in its closed condition. Alternatively one wall part may be coupled merely to form an extension of a component (such as a lid) having the other wall part. Numerous devices have been proposed for coupling together wall parts as aforementioned such as latches, strapping, removable pegs and snap engaging lock devices. It is often considered that known devices are relatively expensive to manufacture and/or assemble, are inconvenient to operate (either or both for coupling or uncoupling of the wall parts), that they form a relatively obtrusive part or projection on the wall parts (either when those parts are uncoupled or coupled together) or that they have a means of coupling that may be mislaid. It is an object of the present invention to provide a wall coupling which is relatively simple and inexpensive to manufacture and assemble, is easy and convenient to operate, that may form a relatively unobtrusive feature of a wall part, and which is unlikely to be accidentally damaged or mislaid.